During surgery, blood, saline, and in some cases, small tissue are evacuated from a subject's body, and collected in a collection container. Typically, this evacuation process is accompanied by suction. The components in the collection canister include at least some volume of blood in most cases. However, the volume of blood included is difficult to assess with any degree of accuracy. Blood loss assessment is critical to the health of the subject, but currently is assessed by only crude techniques associated with the counting of saline units employed during the surgical procedure by the attending health care professional/anesthesiologist. At the conclusion of the surgery, typically the anesthesiologist will estimate the amount of blood lost by determining what volume of saline was used during the surgery overall, and then subtracting this saline volume from the total volume of mixed material collected in the collection canister(s).
Blood is composed of RBCs, and RBCs require a significant amount of time (over 3-6 hours) to settle out of a blood/fluid mixture collected at the time of surgery. Apart from the significant time required to provide even a reading of settled RBC volume, it has been found that the settled RBC volume does not provide an adequate approximation of blood volume for assessing blood needs. Current techniques for estimating blood loss are fraught with challenges, including human error (counting “used” saline bags, accounting for residual saline) and serious time constraints associated with conventional blood-containing fluid analysis.
Failure to accurately approximate blood loss during a surgical event results in a number of potentially serious health complications to the patient, as well as increased medical costs. For example, underestimation of blood loss can result in failure to provide a needed blood transfusion to the subject. This in turn results in the subject, in many cases, becoming anemic, requiring extended hospitalized to stabilize the patient and/or even death. An over estimation of blood loss may result in unnecessary blood transfusions and/or other unnecessary medical interventions, as well as in waste of blood units. Such may also cause increased risk of disease transmission (for example HIV, hepatitis).
The medical arts remain in need of improved techniques and materials to accurately estimate blood loss. Methods for more accurately monitoring and approximating blood volume in a fluid are needed. Fluid collection products suitable for providing a more accurate blood volume approximation are also needed, as will serve to reduce medical costs associated with unnecessary medical treatments and interventions that occur as a result.